This invention relates to the manufacture of ink ribbons, and more particularly to improvements in ink ribbon take-up bodies adapted to take up narrow ink ribbons formed by longitudinal slitting of a wide ribbon.
Recent advances have taken place in the miniaturization of printers, for example printers used in conjunction with digital cameras to produce high-quality printed images rapidly and easily. With miniaturization of printers, the need has arisen for miniaturized ink ribbons.
In general, an ink ribbon for a printer consists of a base made of paper or plastic film, having an ink layer disposed on one side. The ink ribbon is typically made by slitting a wide ribbon to produce plural ribbons of a predetermined smaller width. The narrow ribbons thus produced are usually stored in cassettes for shipment as end products.
This invention is concerned with a take-up body used to take up ink ribbons formed by slitting in the manner described. The wide ribbon prior to slitting and the ink ribbon, which is the narrow ribbon formed by the slitting process, have the same composition, differing from each other only in width.
Wide ribbons are typically slit to form ink ribbons by a slitting device of the kind disclosed in Japanese Patent No. 2726856.
In a conventional wide ribbon slitting device, a wide ink ribbon is unreeled from a supply roll, and slit longitudinally to form plural, separate, narrow, ink ribbons which are wound into reels on take-up cores.
In the slitting operation refuse strips are generated between adjacent ink ribbons. The generation of refuse strips results in the formation spaces between adjacent ink ribbons. Therefore, separators are generally utilized between ribbon take-up cores.
Ribbon cores and separators are installed alternately on an elongate core mounting shaft. Notches formed at axial ends of the ribbon cores are engaged by complementary projections on the separators so that the cores and separators rotate together.
In the assembly process, the ribbon cores and the separators are pushed axially onto the mounting shaft. A pin, extending through a radial bore in the wall of each separator engages a longitudinal groove formed in the core mounting shaft so that the separators and ribbon cores rotate with the shaft.
The assembly of the conventional ink ribbon take-up body is difficult and time-consuming because of the need to fit the projections of the separators into the notches of the ribbon cores, and the need to install the ribbon cores and separators on the shaft in the proper direction so that their respective notches and projections can engage one another.
As mentioned previously, miniaturization of ink ribbons is necessitated by the miniaturization of printers using them. But, there is a practical limit to the size reduction that can be achieved in the core mounting shaft. If the shaft is made too small in diameter, it will not have adequate mechanical strength.
The only alternative is to reduce the wall thickness of the ribbon core. However, since the projections of the separators must engage the notches of the ribbon cores in order for the separators and ribbon cores to rotate together, a relatively large stress is produced at the notches of the ribbon cores. Thus, if the walls of the ribbon cores are made too thin, there is a possibility that the notches will be damaged. Moreover, the reduction of the wall thickness of the ribbon core and the resulting reduction of its mechanical strength may even make it impossible to form the notch in some cases.
The principal object of the invention is to solve the aforementioned problems encountered in conventional ribbon take-up bodies and in efforts to miniaturize such bodies.
The ink ribbon take-up body in accordance with the invention comprises at least one cylindrical ribbon core for taking up a longitudinally slit ink ribbon and a ribbon core mounting shaft. Each ribbon core is mounted on the mounting shaft, and has an inner surface with an engaging part formed thereon. The mounting shaft, in turn, has an outer surface with an engaging part formed thereon. The engaging part of the mounting shaft is complementary to, and engaged with, the engaging part of each ribbon core so that the mounting shaft may rotate integrally with each ribbon core. The ink ribbon take-up body preferably comprises at least two such cylindrical ribbon cores, and at least one cylindrical separator, there being a said separator inserted between the cylindrical ribbon cores of each pair of adjacent ribbon cores. In a preferred embodiment, the engaging part formed on the inner surface of each ribbon core comprises a projection, and the complementary engaging part formed on the outer surface of the mounting shaft comprises a recessed groove. In each case, as a result of the cooperation of their complementary engaging parts, the ribbon cores and the ribbon core mounting shaft rotate as an integral body, and the wound ink ribbon assembly can be miniaturized by reducing the wall thickness of the ribbon core.
Other objects, details and advantages of the invention will be apparent from the following detailed description when read in conjunction with the drawings.